Engines, e.g., diesel or gasoline engines, typically include a fuel delivery system configured to direct fuel into one or more combustion chambers. By combusting the fuel within a variable volume chamber, e.g., a piston-cylinder arrangement, the potential energy associated with the fuel is converted into mechanical power and is typically delivered to one or more engine loads, e.g., traction loads or auxiliary loads. By increasing the amount of fuel delivered to the one or more combustion chambers, an engine can deliver increasing amounts of mechanical power to the associated loads. However, the amount of fuel that can be delivered to an engine is usually limited by one or more constraints, such as, for example, physical constraints, e.g., engine integrity, governmental constraints, e.g., emissions, and/or economical constraints, e.g., fuel efficiency. Often, an engine is operated at a percentage of its fuel limit to deliver power to steady state loads while maintaining an available margin, typically 3-5%, to deliver power to transient auxiliary loads. By restraining an engine to operate below its available power, a substantial portion of available engine power may be infrequently utilized and thus wasted.
U.S. Pat. No. 6,493,627 (“the '627 patent”) issued to Gallagher et al. discloses a variable fuel limit for diesel engines. The method of the '627 patent determines a fuel limit based on ambient temperature and pressure, fuel temperature, fuel heating value, and conditions of a fuel pump and fuel injectors to account for the affects that varying operating conditions have on the volume of fuel delivered to the engine. As such, the method of the '627 patent adjusts the fuel limit as a function of operating conditions to ensure that an ultimate fuel limit, e.g., a predetermined fuel limit, is not artificially decreased when the density of the fuel decreases, e.g., with increasing temperature, or is not artificially increased when the density of fuel increases, e.g., with increasing temperature.
Although the fuel limit determined by the method of the '627 patent may be adjusted based on varying operating conditions, the method of the '627 patent maintains an ultimate fuel limit that will not be exceeded, even in transient situations, potentially leaving a portion of the available engine power under utilized. Additionally, the method of the '627 patent requires sensing operating conditions and/or predicting component wear that may decrease the accuracy of any determined variable fuel limit.
The present disclosure is directed to overcoming one or more of the shortcomings set forth above.